Abstract: A plurality of flow field plate assemblies forms a fuel cell stack. Each flow field plate assembly has a first flow field plate positionable on an anode side of a membrane electrode assembly (MEA) of a first fuel cell, a second flow field plate positionable on a cathode side of an MEA of a second fuel cell, adjacent the first fuel cell. At least one back-feed channel is interposed between the first and second flow field plates. At least a portion of the back-feed channel or a reactant manifold opening formed by the first and second flow field plates has a geometry that forms regions of high and low capillary forces, promoting liquid migration toward regions substantially isolated from a flow of reactants, to prevent water collection and ice formation. The migrated liquid is purged during a purge of the fuel cell stack after operation.

Abstract: Improved water distribution can be obtained within the cells of a fuel cell series stack by maintaining a suitable temperature difference between the cathode and anode sides of each cell in the stack during shutdown. This can be accomplished by thermally insulating the “hot” end and sides of the stack and by providing a thermal mass adjacent to the “hot” end.

Abstract: Improved water distribution can be obtained within the cells of a fuel cell series stack by maintaining a suitable temperature difference between the cathode and anode sides of each cell in the stack during shutdown. This can be accomplished by thermally insulating the “hot” end and sides of the stack and by providing a thermal mass adjacent to the “hot” end.

Abstract: A plurality of flow field plate assemblies forms a fuel cell stack. Each flow field plate assembly has a first flow field plate positionable on an anode side of a membrane electrode assembly (MEA) of a first fuel cell, a second flow field plate positionable on a cathode side of an MEA of a second fuel cell, adjacent the first fuel cell. At least one back-feed channel is interposed between the first and second flow field plates. At least a portion of the back-feed channel or a reactant manifold opening formed by the first and second flow field plates has a geometry that forms regions of high and low capillary forces, promoting liquid migration toward regions substantially isolated from a flow of reactants, to prevent water collection and ice formation. The migrated liquid being is purged during a purge of the fuel cell stack after operation.

Abstract: A flow field plate assembly for use in a fuel cell, a plurality of which can form a fuel cell stack, comprises first and second flow field plates and a body comprising a porous medium interposed between the first and second flow field plates, the porous medium being operable to allow passage of a fuel and an oxygen-containing gas therethrough, and block from passage therethrough, a flow of liquids to prevent water collection and ice formation, which may block passages formed on at least a portion of the first and/or second flow field plates.

Abstract: A fermentation reactor and method for fermentation of materials having greater than about 10% solids. The reactor includes a rotatable shaft along the central axis, the shaft including rods extending outwardly to mix the materials. The reactor and method are useful for anaerobic digestion of municipal solid wastes to produce methane, for production of commodity chemicals from organic materials, and for microbial fermentation processes.